16th International HIV Drug Resistance Workshop 12-16 June 2007, Barbados

IN VITRO CROSS-RESISTANCE STUDIES OF FIVE DIFFERENT CLASSES OF INTEGRASE INHIBITORS IN RECOMBINANT HIV-1

Antivir Ther. 2007; 12:S3 (abstract no. 1)

C Ren, S May, T Miletti and J Bedard
ViroChem Pharma Inc. Laval, QC, Canada

BACKGROUND: Several novel, low molecular weight, potent HIV-1 integrase inhibitors have been reported in the literature. These compounds possess a pharmacophore, which is capable of chelating the divalent metals present in the catalytic site of the enzyme. Despite a common mechanism of action shared by these molecules, in vitro selection studies of HIV-1 variants with reduced susceptibilities to integrase inhibitors have revealed distinct pathways of resistance emergence. Our aim was to investigate the potential cross-resistance of these mutations with five structurally distinct integrase inhibitors.

METHODS: Recombinant HIV-1 integrase mutants were generated by site-directed mutagenesis using HXB-2D proviral clone as starting material. Drug susceptibility was evaluated in MT-2 cells. Cells were infected at a multiplicity of infection of 0.5 for 3 h, washed to remove any residual virus, resuspended in culture medium and seeded into 96-well plates in the presence of various concentrations of the test compound. Thereafter, infected cells were cultured for 3 days after which an aliquot of medium with cells was replaced with fresh medium containing the test compound. The level of HIV-1 replication was determined at day 5 post-infection by measuring the reverse transcriptase activity in the harvested supernatant fluid.

RESULTS: The anti-HIV-1 activity of all compounds tested, namely, L-731,988, GS-9137, MK-0518, L-870-810, and a novel pyridone A, was found to be significantly reduced when tested against HIV HXB-2D mutants carrying the F121Y, F121Y/T125K, V72I/F121Y/T125K, and V151I/V72I/F121Y/T125K mutations, whereas the T66I, T66I/S153Y, T66I/M154I mutants were found to be associated with reduced susceptibility to L-731,988 and GS-9137.

CONCLUSIONS: It is well documented that in vitro resistance development to different chemical series of integrase inhibitors involved specific mutational pathways. In this study, phenotypic analysis of recombinant viruses harbouring selected mutations within the integrase gene has demonstrated significant cross-resistance with the compounds investigated.

2007-06-12
1

Copyright © 2006 - International Medical Press Ltd.. Reproduction of this abstract (other than one copy for personal reference) must be cleared through the International Medical Press Ltd. 2-4 Idol Lane, London EC3R 5DD UK.